The prior art has shown apparatus for producing aerated water for use in a shower head or a kitchen sink faucet, with both being shown in U.S. Pat. No. 2,565,554 by Joseph J. Goodrie, issued Aug. 28, 1951. Some aerating devices have had the air inlets adjacent a perforated disc, as in the Goodrie patent or in U.S. Pat. No. 2,633,343 to Elie P. Aghnides, issued Mar. 31, 1953. Some shower heads have had a spray pattern defined by a plurality of apertures adjacent a chamfered edge of the shower head. Such is illustrated in U.S. Pat. No. 3,322,352 by Jose M. A. Alcantara, issued May 30, 1967. Other shower heads have had diverging streams of water in a shower head, with the shower head having a rounded inner corner. Such construction is shown in U.S. Pat. No. 4,013,120 to John T. Gondek, issued Mar. 22, 1977. A further aerating type of shower head had an outlet aperture with a plurality of conical steps or a cylindrical outlet aperture with a step. This was shown in U.S. Pat. No. 4,082,225 to Kenneth H. Haynes, issued Apr. 4, 1978.
It has been observed that the typical shower head had a chamfered or rounded edge for ease of production and also for protection to the user. A person using a shower head often wishes to take hold of it to adjust the direction of the shower spray, and if sharp edges are present, they may be a possible source of cuts to the hand of the user. Also, during manufacturing or during use, the edges of the shower head might become nicked or scratched, and it has been determined that this disrupts the shower spray pattern from its normal uniform pattern. Such a nick could cause the water to creep back on the outside edge of the spray head, according to Bernoulli's theorem, because the flow pattern of the water leaving the exit end of the spray head was disrupted.